android phone with eclipse debugging always show offline

I spent two phones to debug a program , but one always shows offline, can not debug . Students can also use the phone to debug . And now 360 mobile assistant can not connect the phone , do not know how this will suddenly yesterday can still connect . I've been reset adb still can not connect , turn off the adb reboot as well. Do not know how children ?
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re- installed under the driver
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adb conflict , 360 and Tencent helper class software , often affect the development
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Do debug switch your phone off ?
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no off, the computer may be the reason , even on today's show online and then , at that time under the computer should restart . Although I still do not know why.
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last generally how to solve ah